Samsung Heat Pump Error Code E403

E403 means the compressor has been shut down by the system's compression ratio protection control. The ratio of (High pressure + 1) divided by (Low pressure + 1) exceeded 8.5 for more than 10 minutes, triggering a protective shutdown. This is designed to prevent compressor damage from operating under extreme pressure imbalance. A technician should connect diagnostic tools and check refrigerant pressures and service valve positions to identify the underlying cause.

No, the unit has already shut down the compressor as a protective measure and should not be forced to restart repeatedly. Continuing to operate the system under conditions that cause an abnormal compression ratio risks serious compressor damage. Leave the unit off and have a technician diagnose the issue before resuming normal operation.

A power reset may temporarily clear the code and allow the compressor to restart, but the error will return if the underlying condition causing the high compression ratio is not corrected. Because the fault requires the ratio to exceed 8.5 for over 10 minutes before triggering, repeated resets without repair will continue to stress the compressor. A proper diagnosis and repair are necessary for a lasting resolution.

Some basic checks, like confirming that the service valves are fully open, can be done without specialized tools. However, diagnosing refrigerant charge issues, checking pressure transducers, and handling refrigerant require EPA certification and professional equipment such as a manifold gauge set and S-net diagnostic software. Most homeowners should contact a certified HVAC technician for this error.

Repair cost depends entirely on the root cause. A simple service valve adjustment or coil cleaning may cost only a service call fee, typically in the range of $75 to $200. Refrigerant leak repair and recharge can range from $200 to $600 or more depending on the refrigerant type and leak location. Pressure transducer replacement generally falls in the $150 to $400 range including parts and labor.